#多态
class Animal:
    def speak(self):
        print("叫")

class Dog(Animal):
    def speak(self):
        print("汪汪汪")

class Cat(Animal):
    def speak(self):
        print("喵喵喵")

dog = Dog()
cat = Cat()

def doing(Animal):
    Animal.speak()

doing(dog)
doing(cat)



